Catheters are flexible medical instruments for use in the withdrawal and introduction of fluids to and from body cavities, ducts, and vessels. Catheters have particular application in hemodialysis procedures, in which blood is withdrawn from a blood vessel for treatment and subsequently returned to the blood vessel for circulation through a patient's body. Catheters may also be used for other procedures and include central venous catheters, dialysis catheters, peripheral catheters and neurology catheters.
Various techniques are employed for the insertion of catheters into the body including, but not limited to, the use of guidewires, introduction stylets or obturators, dilator/sheath assemblies, and the like. For example, during such procedures, a hollow needle cannula may be inserted into a target vessel in, for example, the venous system, to create a venotomy (entry) site. Upon positioning the needle cannula within the target vessel, a guidewire is inserted through a proximal end of the needle cannula, into the target vessel, and advanced to a desired location within the target vessel. The needle cannula is then withdrawn, leaving a distal end of the guidewire positioned within the target vessel at the desired location, and a proximal end of the guidewire extending outwardly from the venotomy site. A dilator/sheath assembly is then threaded over the guidewire and into the vessel through the venotomy site to expand the venotomy site and target vessel to help insert the flexible catheter. The separate dilator within the sheath provides the structure at the distal end of the sheath to push through and expand the tissue. The guidewire and dilator are then retracted from the site, leaving the sheath in position. The sheath typically includes a hemostatic valve to reduce the loss of blood and the aspiration of air therethrough as the dilator is removed and before a catheter or other instrument is inserted into the sheath. A catheter may then be introduced through the hemostatic valve and sheath, and advanced into position within the target vessel at which time the sheath may be withdrawn from the vessel over the catheter such that the distal tip of the catheter remains in place within the vessel.
Although known insertion techniques have proven to be effective, it would be advantageous to provide a device to enable for the insertion of the catheter into the circulatory system without the need for a separate dilator/obturator or hemostatic valve, thereby reducing the number of insertion accessories, procedure time, and cost. Such a device would enable the successful insertion of catheters having various tip designs (e.g., blunted, non-tapered, or split tips) to be inserted directly into the vasculature with the sheath. The device would also enable the successful insertion of catheters fabricated from various materials as the device may be provided with varying degrees of stiffness. A stiffer device, for example, may replace the need to use a stylet during insertion of softer catheters thereby further reducing the cost of a catheter kit, the number of components a clinician has to interact with during a catheterization procedure, and the procedure time.